The invention relates to a plasma torch for the high-frequency capacitive generation of a plasma beam, comprising a housing which includes a holder and an electrically non-conducting nozzle, the housing having an inlet aperture and the nozzle having an outlet aperture, and also a rod-shaped electrode which is arranged coaxially with respect to the housing.
Plasma torches for generating plasma beams are used in various industrial fields such as the local heating -0 of materials, welding and cutting, working and shaping glass including quartz glass, and flame spraying of materials. In a plasma torch plasma beams can be generated inductively or capacitively or by means of direct current.
German Offenlegungsschrift 1 765 104, corresponding to British Patent No. 1,218,661, discloses a device for capacitively generating a plasma beam. To that end, an exterior oscillator circuit of a high-frequency generator is connected to a tungsten electrode. A gas is passed along the electrode. In response to electric resonance a high electric voltage is produced at the electrode, causing the passing gas to be ionized. The electrode is enveloped by an electrically non-conducting tube. One side of the tube is provided with a nozzle, not further described, from which the plasma beam can escape. The plasma beam is brought into contact with a workpiece to be worked, the circuit being capacitively closed via the work piece. The said Offenlegungsschrift specifies a nozzle-workpiece distance of 5-15 mm.